I use the SD card for storage so that is not the problem. I always edit a copy of the original so I can start over if I really screw it up.
I confess that I have not even tried the editing capabilities of Go 4 because it resides on an underpowered Tab A, I would rather use my computer for the larger monitor, keyboard, mouse, and my tablet does not meet the minimum requirements for Resolve. If you have not tried Resolve, check it out on YouTube. For a free program it is amazing.